Cutting torch nozzle and method



Jan. 23, 1968 DQMBRUCH ET AL 3,364,970

CUTTING TORCH NOZZLE AND METHOD Filed April 5, 1967 'F' .5. F' 45 H R Z United States Patent 3,364,979 CUTTING TORCH NOZZLE AND METHOD Franz Domhruch, ()tfenbach am Main, Traugott Gutermann, Frankfurt am Main, and Karl Teslre, Hoflreim, Taunus, Germany, assignors to Messer Griesheim G.m.h.H., Frankfurt am Main, Germany, a corporation of Germany ontinuation-in-part of application Ser. No. 389,859,

Aug. 17, 1964. This application Apr. 3, 1967, Ser.

11 Gaims. (Cl. 158-27.4)

ABSTRACT 0F THE DTSCLOSURE A cutting torch nozzle includes a central stream of high velocity cutting oxygen, an intermediate annular stream of intermediate velocity fuel gas surrounding the cutting oxygen, and an outer annular stream of slower velocity additional oxygen surrounding the fuel gas. The fuel gas mixes externally with the oxygen supplied from both the central cutting stream and the outer additional stream by being sucked into the outer partsof the cutting oxygen stream and by drawing oxygen from the outer stream. The outer stream also acts as a shield for the fuel gas to assure its complete combustion and minimize mixture with the air which would result in undesired carbon deposits or soot.

Cross-reference to related application This application is a continuation-in-part of copending application Ser. No. 389,859, filed Aug. 17, 1964 and now abandoned.

Background of the invention This invention relates to a nozzle for a metal cutting torch such as for plate cutting, and more particularly to such a cutting torch which externally mixes oxygen with its fuel.

In cutting and flame torches it is often customary to use an oxygen stream and post-mixed preheating flames, that is flames formed by the combustion fuel gas and oxidizing gas mixed externally of the nozzle, in order to avoid the formation of an inflammable gas mixture within the torch, and hence undesirable reactions in the torch such as backflring. Some torches do not add a special heating oxygen stream to the fuel but instead construct the nozzle head in such a manner that the fuel obtains the oxygen necessary for orderly combustion, from the actual cutting or flame oxygen stream. This is achieved in a simple manner in that the fuel as well as the cutting or flame oxygen stream openings are situated so close to each other that the flames are formed immediately at the edge area of the oxygen stream.

The use of this principle of outside mixture has very good results in working with an oxygen stream having slight exhaust speed, as is often used in flame torches for instance, particularly in the use of acetylene or gases burning slower than acetylene, such as coal gas, propane or the like. There are difliculties, however, in cases where a high heat tolerance and heat concentration and where a sufficient combustion of the gas in not too great a distance from the work piece, are required with the oxygen streams having high velocity as is the case, for example, in torch cutting.

Devices are known which include outer streams of fuel gas or an outer stream of premixed gases. One such device is disclosed in US. Patent 2,407,972. This device is intended for operation in a longitudinal or axial direction for piercing or cutting holes. The arrangement includes a central stream of cutting oxygen, an intermediate stream of fuel gas and an outer stream of addi- 3,364,973 Patented Jan. 23, 1968 tional oxygen within the torch nozzle. However the fuel gas and additional oxygen streams are so arranged that they mix internally within the nozzle tip resulting in only two streams being emitted from the nozzle tie. the cutting oxygen stream and the mixed preheat stream). Accordingly when the streams are emitted there is no assurance of complete combustion of the fuel gas since the amount of oxygen supplied to it at the tip of the torch may not be suflicient for maximum burning. Such an arrangement thereby results in undesirable carbon deposits or soot. A further undesirable feature of this torch is the requirement of cooling streams.

Another patent in this field is US. Patent 2,243,184 which relates to a method of making blowpipe nozzles which had formerly been swaged to provide a central cutting oxygen passage and a series of preheat passages. This type of nozzle would be similar to that of US. Patent 2,407,972 in that both cutting oxygen and mixed gases are emitted from the nozzle. With such arrangements, even where the passages are coterminous, flash back could occur due to the presence of mixed gases in a passageway.

An object of this invention is to provide a nozzle for effectively mixing fuel with oxygen streams outside a metal cutting torch.

Summary of the invention In accordance with this invention a constantly satisfactory flame formation is achieved, irrespective of the fuel used, in cutting torches by means of a nozzle having one or more further oxygen exhaust openings closely arranged to the fuel exhaust openings with correspondingly the fuel exhaust openings surrounding the central cutting oxygen passage. In other words the fuel is concentrically arranged between two streams of oxygen. The cutting oxygen is emitted at high speed, the fuel gas at intermediate speed, and the additional oxygen at lower speed. Thus correlation is brought about in that the areas of the emerging fuel gases which are diverted from the central cutting oxygen stream also come in contact with the additional oxygen stream to thereby achieve by a double outer mixture a satisfactory intermixture fuel gas and oxygen.

Because of the relative speeds of the gases, a large turbulence is created between the fast moving cutting oxygen and the slower moving fuel which thus sucks the fuel gas toward the outer parts of the cutting oxygen to facilitate an external mixing of most of the fuel gas. The difference in relative speed between the fuel gas and outer additional oxygen results in sufficient additional oxygen being sucked into the faster moving fuel gas to assure a complete mixing of the otherwise unmixed fuel gas. Since the outer stream of oxygen is slow moving, there is only a slight ditference in speed between the additional oxygen and the surrounding atmosphere whereby little air is drawn into the additional oxygen and none penetrates to mix with the fuel gas. This arrangement enables the formation of a relatively long flame having a concentrated stream of cutting oxygen which is particularly suitable for cutting plates without undesirable carbon deposits.

As is apparent from the above, the intermediate fuel stream thereby mixes with oxygen from the central cutting ream as well as with oxygen from the outer annular stream. The outer stream of oxygen thus has the added function of shielding the fuel from the air which assures a complete combustion or mixing of the fuel while preventing the formation of carbon deposits or soot. For example arrangements which contain outer streams of fuel gas or of premixed gases (such as disclosed in US. Patents 2,407,972 and 2,243,184) permit a mixture of the air and fuel gas. Since air contains over 70% nitrogen and other inert gases there is an incomplete combustion in that the fuel gas is not fully oxidized. This in turn results in carbon formations or soot on the Workpiece which increases the strength of the workpiece rendering it more diflicult to cut or work with at some subsequent time. Additionally the type of cut achieved with such prior devices would be wavy and of varying thickness or non-uniform due to the instable fluttering of the pre-heat mixture. With the shielded fuel stream of this invention there is complete combustion which enables a smooth. sharp, uniform, narrow cut to be obtained from the more concentrated cutting stream.

In one form of this invention the nozzle tip for the cutting torch is constructed by providing the additional oxygen exhaust openings concentrically around the round fuel gas exhaust slot or the ring of individual Openings for fuel gas exhaust, either in the form of an annular passage or a number of individual passages of any diameter desired. When the fuel gas exhaust is made up of a ring of individual openings or passages, the additional oxygen exhaust openings may be arranged in the ring area of the fuel gas openings in an alternating manner. In other words all of the additional oxygen exhaust openings are not radially aligned with the fuel openings. In all of these arrangements of the additional oxygen exhaust openings and the fuel gas opening there results in an especially effective manner a double outer mixture, irrespective of the central cutting oxygen passageway.

This double outer mixture may also be accomplished by constructing the nozzle tip for the cutting torch with the additional oxygen exhaust openings concentrically surrounding the round fuel gas exhaust slot or the ring of individual openings for the fuel gas exhaust, either in the form of an annular opening or a number of individual openings of any cross section desired.

Other objects and many attendant advantages of this invention will be readily appreciated as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

Brief description of drawing FIGS. 1-3 are cross-sectional views of three embodiments of this invention;

FIG. 4 is a side view partially broken away and in section of the nozzle shown in FIG. 3;

FIG. 5 is a side view of a modified nozzle similar to FIG. 4;

FIG. 6 is an elevation view partly in section of a nozzle in accordance with this invention during operation; and

FIGS. 7-8 are perspective views of the resulting cuts from a nozzle in accordance with this invention and in accordance with the prior art, respectively.

Detailed description of the invention FIG. 4 shows the general arrangement of a cutting torch head 10 incorporating one of the nozzles 11 of this invention. As shown in FIG. 4 cutting oxygen is supplied through conduit 7 into central bore 1 of torch head 10 and nozzle 11. Conduit 8 conducts the gaseous fuel through a number of apertures or passages 12 which are concentric with central oxygen cutting passageway 1. Additional oxygen is supplied through conduit 9 into spaced passages 23 in jacket 26 concentrically arranged about passages 12.

FIG. 5 shows a nozzle similar to that of FIG. 4, differing, however, in that passageways 12a and 23a are parallel to, and not inclined toward, central outlet 1.

FIG. 1 show-s one form of a nozzle Where there are arranged around the central cutting oxygen bore or passage 1, an annular or ring-like passage or slot 2 for fuel gas in place of individual passages. Surrounding passage 2 is another annular channel 3 for supplying the additional heating oxygen.

The nozzle tip represented in FIG. 2 is constructed in two parts. The actual cutting nozzle 4, which contains the central cutting oxygen bore 1, is provided with slots or grooves 12 ,on its outer surface. Heating cap 5 is secured to and surrounds nozzle -4 to thus transform slots or grooves 12 into closed canals or passages for the fuel gas. Cap 5 also has a plurality of grooves or slots 13 on its outer surface which, in turn become canals or passages for the additional oxygen when jacket 6 is screwed on or otherwise secured on or otherwise secured to cap 5.

FIG. 3 is a cross-sectional view of the nozzle 11 shown in FIG. 4 and includes a sleeve 26 surrounding cutting nozzle 4 which contains central oxygen passage 1. Nozzle 4 is provided with spaced longitudinal grooves 12 which :form fuel passages when jacket 26 is secured to nozzle.

4. Sleeve or jacket 26 has a series of spaced longitudinal passages 23 which conduct the additional oxygen. In this arrangement the need for a special heating cap such as cap 5 of FIG. 2, is eliminated.

By means of the nozzles shown, there is achieved in an especially advantageous manner a double outer mixture of the fuel gas. The pure fuel gas, leaving slot or annular passage 2 or canals 12, obtains its heating oxygen in the usual manner from the edge area of the central cutting oxygen stream, which streams through bore 1. Additionally, however, for the obtainment of a suflicient mixture, there is mixed to the fuel gas additional oxygen which passes through annular passageway 3, or canals 13, or bores 23. This additional oxygen not only provides an added supply of oxygen to the fuel but also shields the fuel from the surrounding air.

FIG. 6 shows the use of nozzle 11 in cutting, for example, metal plate 30. As indicated therein a relatively long concentrated flame 32 can out completely through plate 30 with the resultant cut being similar to cut 36 of FIG. 7. As is apparent from FIG. 7 cut 36 is smooth, sharp, symmetrical and narrow in striking contrast to the type of cut, such as cut 34, achieved with prior art devices where the fuel gas is not shielded from the surrounding atmosphere by additional oxygen. The plate 40 of FIG. 8 has soot or carbon deposits on the walls of cut 34 which undesirably increases its strength which makes plate 40 more difficult to cut at some later time. The strength of plate 38, however, is not affected by cut 36. Cut 34 is also relatively wide and of non-uniform quality with waviness and thickness variations due to the unstable fluttering from preheat mixtures. For example the corners of cut 34 are rounded because the cutting oxygen stream is not as concentrated and the preheating flame is broader than flame 32 of FIG. 6.

The complete mixing of the fuel gas with oxygen is facilitated by decreasing the stream velocity from the inner stream toward the outer stream. Advantageously the speed of the cutting oxygen is at least five times higher than the speed of the fuel gas, while the speed of the fuel gas is at least two, times higher than the speed of the additional oxygen. For example where acetylene is used as the fuel gas, the speed of the cutting oxygen is over 300 in. per sec., while the speed of the acetylene is from 50-60 in. per sec., and the speed of the additional oxygen is from 20-35 m. per sec. The large turbulence created by the difference in relative speed between the cutting oxygen and the fuel gas results in about of the fuel gas being mixed, while the remaining V3 mixes with additional oxygen due to the turbulence caused by the difference in relative speed between the fuel gas and slower moving additional oxygen.

The invention can be efiected in various ways and is not limited to the examples shown. Thus, the arrangement and diameter size of the exhaust canals or passages for the actual cutting oxygen, fuel gas, as well as additional oxygen are entirely arbitrary and depend on the requirements and circumstances of a particular case. For

example, the exhaust openings for the additional oxygen can be installed in the same exhaust ring or annular'memher as the fuel gas, particularly in such a manner that the gas and oxygen exhaust openings are alternatively arranged. For example as shown in FIGS. 2-3' all of the additional oxygen passageways 13 or 23 are not radially aligned with fuel passageways 12. In all cases it is also essential that the nozzle tipnext to the cutting oxygen exhaust-is at a suitable place, or in the corresponding area of the further oxygen exhaust openings, to enable a double outer mixture of the fuel gas.

Similarly, the principle of the double outer mixture can be used for torches of other types and nature, e.g. for flame torches or the like. This concept can thus be used in cases where any other cross-section forms for the gas and oxygen exhaust are present, such as elongated exhaust slots for the oxygen with heating gas exhaust openings in the form of bores or slots mounted above and/ or below the oxygen exhaust openings.

The nozzle of this invention which enables such double outer mixture is not only of importance in the use of gases with more slight exhaust velocity as acetylene; but also in the use of acetylene, the comparatively high oxidation velocity of the acetylene does not ordinarily prevent an incomplete oxidation forming undesired carbon deposits or soot on the workpiece. This carbon deposit is avoided, however, in the use of an outer oxygen sheet around the acetylene, and there occurs, furthermore, because of the additional oxygen, an intensive burning and thus makes a better utilization (i.e. complete combustion) of the acetylene. The nozzle of this invention is, of course, not limited to a particular type of fuel gas.

Fina ly, by means of correspondingly logical arrangement of the further fuel gas, and oxygen exhaust openings adjacent thereto, the double outer mixture can be extended to a multiple outer mixture, as it is considered for example in preheating torches with large effective surfaces.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A nozzle for a torch operated by the external mixing of its gases comprising a central cutting oxygen stream outlet, a plurality of gas passageways concentrically arranged about said central outlet for conducting a corresponding number of unmixed gases from the torch, said outlet and said passageways being coterminous whereby internal mixing is avoided, said central outlet having a feed end and a discharge end, means connected to said feed end for feeding cutting oxygen gas through said outlet at a relatively high speed, said plurality of passageways comprising a pair of passageways, one of said passageways being an intermediate passageway concentrically arranged between one of the said passageways and said central outlet, the other of said passageways being an outer passageway, means connected to the feed end of said intermediate passageway for feeding fuel gas therethrough at an intermediate speed, and means connected to the feed end of said outer passageway for feeding additional oxygen therethrough at a relatively low speed.

2. A nozzle as set forth in claim 1 wherein said intermediate passageway is a continuous annular passageway.

3. A nozzle as set forth in claim 1 wherein said outer additional oxygen passageway is a continuous annular passageway.

4. A nozzle as set forth in claim 1 wherein said cutting oxygen outlet is a bore in a central member, a plurality of longitudinal grooves being in the external surface of said central member, a sleeve fitting over said central member to form a top wall for said grooves, and said plurality of grooves being said intermediate passageway for said fuel gas.

5. A nozzle as set forth in claim 4 wherein a second plurality of grooves are in the external surface of said sleeve, an outer member fitting over said sleeve to form a top wall for said second plurality of grooves, and said second plurality of grooves being said outer passageway for additional oxygen.

6. A nozzle as set forth in claim 1 wherein said intermediate fuel passageway is a set of spaced coarcuate passageways, said outer additional oxygen passageway being a set of spaced coarcuate passageways, and at least some of said additional oxygen passageways being radially nonaligned with corresponding fuel passageways.

7. In a process for externally mixing gases from a torch nozzle comprising supplying a cutting stream of oxygen through a central outlet in the nozzle at a relatively high speed, supplying an intermediate annular stream of fuel gas through a passageway around said central outlet at an intermediate speed, supplying an outer annular stream of additional oxygen through a passageway around said fuel gas passageway at a relatively low speed, mixing said fuel gas externally of said nozzle with oxygen from both said central stream and said outer stream, and shielding said fuel gas from the atmosphere by said outer stream of additional oxygen.

8. In a process as set forth in claim 7 wherein only unmixed gases are emitted from said nozzle.

9. In a process as set forth in claim 7 wherein the speed of said cutting oxygen is at least five times higher than the speed of said fuel gas, and the speed of said fuel gas is at least two times higher than the speed of said additional oxygen.

10. In a process as set forth in claim 7 including externally mixing about of said fuel gas with oxygen from said cutting oxygen, and mixing about /3 of said fuel gas with oxygen from said additional oxygen.

11. In a process as set forth in claim 7 including cutting a plate by moving said nozzle transversely over said plate.

References Cited UNITED STATES PATENTS 2,243,184 5/1941 Aronson et al. 158-27.4 X 2,365,942 12/1944 Crowe 15827.4 2,407,972 9/ 1946 Aitchison l5 827.4 2,484,891 10/1949 Jones 15827.4 3,204,682 9/1965 Teleshefsky 15 827.4

FOREIGN PATENTS 132,793 9/ 1919 Great Britain.

FREDERICK L. MATIESON, JR., Primary Examiner. E. G. FAVORS, Assistant Examiner. 

